Stent mounting device

ABSTRACT

A stent mounting device and a method of coating a stent using the device are provided.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a stent mounting device and a method ofcoating a stent using the device.

[0003] 2. Description of the Background

[0004] Blood vessel occlusions are commonly treated by mechanicallyenhancing blood flow in the affected vessels, such as by employing astent. Stents act as scaffoldings, functioning to physically hold openand, if desired, to expand the wall of the passageway. Typically stentsare capable of being compressed, so that they can be inserted throughsmall lumens via catheters, and then expanded to a larger diameter oncethey are at the desired location. Examples in the patent literaturedisclosing stents include U.S. Pat. No. 4,733,665 issued to Palmaz, U.S.Pat. No. 4,800,882 issued to Gianturco, and U.S. Pat. No. 4,886,062issued to Wiktor.

[0005]FIG. 1 illustrates a conventional stent 10 formed from a pluralityof struts 12. The plurality of struts 12 are radially expandable andinterconnected by connecting elements 14 that are disposed betweenadjacent struts 12, leaving lateral openings or gaps 16 between adjacentstruts 12. Struts 12 and connecting elements 14 define a tubular stentbody having an outer, tissue-contacting surface and an inner surface.

[0006] Stents are used not only for mechanical intervention but also asvehicles for providing biological therapy. Biological therapy can beachieved by medicating the stents. Medicated stents provide for thelocal administration of a therapeutic substance at the diseased site.Local delivery of a therapeutic substance is a preferred method oftreatment because the substance is concentrated at a specific site andthus smaller total levels of medication can be administered incomparison to systemic dosages that often produce adverse or even toxicside effects for the patient.

[0007] One method of medicating a stent involves the use of a polymericcarrier coated onto the surface of the stent. A composition including asolvent, a polymer dissolved in the solvent, and a therapeutic substancedispersed in the blend is applied to the stent by immersing the stent inthe composition or by spraying the composition onto the stent. Thesolvent is allowed to evaporate, leaving on the stent strut surfaces acoating of the polymer and the therapeutic substance impregnated in thepolymer.

[0008] A shortcoming of the above-described method of medicating a stentis the potential for coating defects. While some coating defects can beminimized by adjusting the coating parameters, other defects occur dueto the nature of the interface between the stent and the apparatus onwhich the stent is supported during the coating process. A high degreeof surface contact between the stent and the supporting apparatus canprovide regions in which the liquid composition can flow, wick, andcollect as the composition is applied. As the solvent evaporates, theexcess composition hardens to form excess coating at and around thecontact points between the stent and the supporting apparatus. Upon theremoval of the coated stent from the supporting apparatus, the excesscoating may stick to the apparatus, thereby removing some of the coatingfrom the stent and leaving bare areas. Alternatively, the excess coatingmay stick to the stent, thereby leaving excess coating as clumps orpools on the struts or webbing between the struts.

[0009] Thus, it is desirable to minimize the potential for coatingdefects generated by the interface between the stent and the apparatussupporting the stent during the coating process. Accordingly, thepresent invention provides for a device for supporting a stent duringthe coating application process. The invention also provides for amethod of coating the stent supported by the device.

SUMMARY OF THE INVENTION

[0010] The present invention provides an apparatus for supporting astent during a process of coating the stent. The apparatus includes amember for supporting a stent during the coating process, wherein asection of the member includes a porous surface capable of receiving thecoating substance during the coating process. The pores can have adiameter between about 0.2 microns and about 50 microns.

[0011] In one embodiment, the member includes a first member for makingcontact with a first end of the stent and a second member for makingcontact with a second end of the stent. In such an embodiment, the porescan be located on at least a region of the surface of the first orsecond members. The first or second member can be made from a metallicmaterial such as 300 Series stainless steel, 400 Series stainless steel,titanium, tantalum, niobium, zirconium, hafnium, and cobalt chromiumalloys. The first or second member can also be made from a polymericmaterial such as, but not limited to, regenerated cellulose, celluloseacetate, polyacetal, polyetheretherketone, polyesters, highly hydrolyzedpolyvinyl alcohol, nylon, polyphenylenesulfide, polyethylene,polyethylene terephthalate, polypropylene, and combinations thereof. Thefirst or second member can also be made from ceramics such as, but notlimited to, zirconia, silica, glass, sintered calcium phosphates,calcium sulfate, and titanium dioxide. In another embodiment, a layercan be disposed on the surface of the first or second member to absorbcoating material that comes into contact with the layer.

[0012] In one embodiment, the first and second members have inwardlytapered ends that penetrate at least partially in the first and secondends of the stent and are in contact with the first and second ends ofthe stent. In another embodiment, the apparatus additionally includes athird member for extending within the stent and for securing the firstmember to the second member.

[0013] The present invention also provides a method of coating a stent.The method includes positioning a stent on a mounting assembly, whereina section of the mounting assembly includes a porous surface. The methodadditionally includes applying a coating composition to the stent,wherein at least some of the coating composition that overflows from thestent is received by the pores. The act of applying a coatingcomposition can include spraying the composition onto the stent.

[0014] In one embodiment, the method also includes at least partiallyexpanding the stent prior to the act of applying. The method can alsoinclude rotating the stent about the longitudinal axis of the stentduring the act of applying and/or moving the stent in a linear directionalong the longitudinal axis of the stent during the act of applying.

[0015] Also provided is a support assembly for a stent. The supportassembly includes a member for supporting a stent, wherein the memberincludes an absorbing layer for at least partially absorbing some of thecoating material that comes into contact with the absorbing layer.

BRIEF DESCRIPTION OF THE FIGURES

[0016]FIG. 1 illustrates a conventional stent.

[0017]FIG. 2A illustrates a mounting assembly for supporting a stent inaccordance with one embodiment of the present invention.

[0018]FIG. 2B illustrates an expanded view of the mounting assembly inaccordance with one embodiment of the present invention.

[0019]FIG. 3A illustrates the interface between the mounting assemblyand the stent.

[0020]FIG. 3B is a cross-sectional view of the interface between themounting assembly and the stent in FIG. 3A.

[0021]FIG. 4A illustrates a fluid on a solid substrate having a contactangle φ_(A);

[0022]FIG. 4B illustrates a fluid on a solid substrate having a contactangle φ_(B);

[0023]FIG. 5 illustrates an end view of a coning end portion having aporous covering over the outer surface thereof.

DETAILED DESCRIPTION Embodiments of the Mounting Assembly

[0024] Referring to FIG. 2A, a mounting assembly 18 for supporting stent10 is illustrated to include a support member 20, a mandrel 22, and alock member 24. Support member 20 can connect to a motor 26A so as toprovide rotational motion about the longitudinal axis of stent 10, asdepicted by arrow 28, during the coating process. Another motor 26B canalso be provided for moving support member 20 in a linear direction,back and forth, along a rail 29. The type of stent 10 is not of criticalimportance and can include radially expandable stents and stent-grafts.

[0025] Referring to FIG. 2B, support member 20 includes a coning endportion 30, tapering inwardly at an angle φ₁ of about 15° to about 75°,more narrowly from about 30° to about 60°. By way of example, angle φ₁can be about 45°. In accordance with one embodiment, mandrel 22 can bepermanently affixed to coning end portion 30. Alternatively, supportmember 20 can include a bore 32 for receiving a first end 34 of mandrel22. First end 34 of mandrel 22 can be threaded to screw into bore 32.Alternatively, a non-threaded first end 34 and bore 32 combination canbe employed such that first end 34 can be press-fitted orfriction-fitted within bore 32 to prevent movement of stent 10 onmounting assembly 18. Bore 32 should be deep enough so as to allowmandrel 22 to securely mate with support member 20. The depth of bore 32can also be over-extended so as to allow a significant length of mandrel22 to penetrate bore 32. This would allow the length of mandrel 22 to beadjusted to accommodate stents of various sizes. In commercialembodiments, support member 20 can be disposable or capable of beingcleaned after each use, for example in a solvent or oxidizing bath, orby pyrolizing out any absorbed coating materials via heating at hightemperatures.

[0026] The outer diameter of mandrel 22 should be smaller than the innerdiameter of stent 10 so as to prevent the outer surface of mandrel 22from making contact with the inner surface of stent 10. A sufficientclearance between the outer surface of mandrel 22 and the inner surfaceof stent 10 should be provided to prevent mandrel 22 from obstructingthe pattern of the stent body during the coating process. By way ofexample, the outer diameter of mandrel 22 can be from about 0.010 inches(0.254 mm) to about 0.017 inches (0.432 mm) when stent 10 has an innerdiameter of between about 0.025 inches (0.635 mm) and about 0.035 inches(0.889 mm).

[0027] Lock member 24 includes a coning end portion 36 having aninwardly tapered angle φ₂. Angle φ₂ can be the same as or different thanthe above-described angle φ₁. A second end 38 of mandrel 22 can bepermanently affixed to lock member 24 if end 34 is disengagable fromsupport member 20. Alternatively, in accordance with another embodiment,mandrel 22 can have a threaded second end 38 for screwing into a bore 40of lock member 24. Bore 40 can be of any suitable depth that would allowlock member 24 to be incrementally moved closer to support member 20.Accordingly, stents 10 of any length can be securely pinched betweensupport and lock members 20 and 24. In accordance with yet anotherembodiment, a non-threaded second end 38 and bore 40 combination isemployed such that second end 38 can be press-fitted or friction-fittedwithin bore 40. In commercial embodiments, lock member 24 can bedisposable or capable of being cleaned after each use.

[0028] Mounting assembly 18 supports stent 10 via coning end portions 30and 36. FIGS. 3A and 3B illustrate the interface between coning endportions 30 and 36 and each end of stent 10 so as to provide minimalcontact between stent 10 and mounting assembly 18. Opposing forcesexerted from support and lock members 20 and 24, for securely pinchingstent 10, should be sufficiently strong so as to prevent any significantmovement of stent 10 on mounting assembly 18. However, the exerted forceshould not compress stent 10 so as to distort the body of stent 10. Overor under application of support force can lead to coating defects, suchas non-uniformity of the coating thickness.

[0029] In addition to supporting stent 10 with minimal contact, coningend portions 30 and 36 also function to reduce buildup of coatingmaterials at the stent 10-mounting assembly 18 interface. Coning endportions 30 and 36 should be able to absorb the coating substanceapplied to stent 10. Thus, excess coating substance is absorbed intoconing end portions 30 and 36 and drawn away from stent 10 during thecoating process, further minimizing the potential for webbing and othercoating defects at the interface between stent 10 and mounting assembly18.

[0030] In one embodiment, the particular material selected for coningend portions 30 and 36 can be any material having a plurality of pores44 suitable to receive or absorb the coating substance deposited thereonduring the coating process. Pores 44 can be interconnected.Interconnected pore structures are also known as open pore systems asopposed to closed pore systems in which pores 44 are isolated from oneanother. Interconnected pores 44 provide a network for moving andholding the coating substance, thus enabling coning end portions 30 and36 to hold a larger amount of the coating substance than coning endportions 30 and 36 having discrete pores 44, each with a fixed capacityfor uptake of the substance. The diameter of pores 44 can be from about0.2 microns to about 50 microns, for example about 1 micron.

[0031] Coning end portions 30 and 36 can be made of materials having aporous body or porous surfaces. Such materials can include ceramics,metals, and polymeric materials. In accordance with another embodiment,support member 20, mandrel 22, and/or lock member 24 can also be made tohave a porous surface. Examples of suitable ceramics include, but arenot limited to, zirconia, silica, glass, sintered calcium phosphates,calcium sulfate, and titanium dioxide.

[0032] Examples of suitable metals include, but are not limited to, 300Series stainless steel, 400 Series stainless steel, titanium, tantalum,niobium, zirconium, hafnium, and cobalt chromium alloys. Surfaces havingpores 44 can be made, for example, by sintering pre-formed metallicparticles together to form porous blanks that can then be machined to asuitable shape or by sintering metallic particles together in asuitably-shaped mold. In alternative embodiments, the metal can beetched or bead-blasted to form a porous surface. Etching can beconducted by exposing the surface to a laser discharge, such as that ofan excimer laser, or to a suitable chemical etchant.

[0033] Examples of suitable polymeric materials include, but are notlimited to, regenerated cellulose, cellulose acetate, polyacetal,polyetheretherketone, polyesters, highly hydrolyzed polyvinyl alcohol,nylon, polyphenylenesulfide, polyethylene, polyethylene terephthalate,polypropylene, and combinations thereof. Methods of making polymershaving pores 44, such as by foaming, sintering particles to form aporous block, and phase inversion processing, are understood by one ofordinary skill in the art. The polymeric material selected should not becapable of swelling, dissolving, or adversely reacting with the coatingsubstance.

[0034] In one suitable embodiment, the polymeric material from which thecomponents are made is selected to allow the coating substance to have ahigh capillary permeation when a droplet of the coating substance isplaced thereon. Capillary permeation or wetting is the movement of afluid on a solid substrate driven by interfacial energetics. Capillarypermeation is quantitated by a contact angle, defined as an angle at thetangent of a droplet in a fluid phase that has taken an equilibriumshape on a solid surface. A low contact angle indicates a higher wettingliquid. A suitably high capillary permeation corresponds to a contactangle less than about 90°. FIG. 4A illustrates a droplet 46 of thecoating substance on a flat, nonporous surface 48A composed of the samematerial as coning end portion 30 or 36. Fluid droplet 46 has a highcapillary permeation that corresponds to a contact angle φ_(A), which isless than about 90°. By contrast, FIG. 4B illustrates fluid droplet 46on a surface 48B having a low capillary permeation that corresponds to acontact angle φ_(B), which is greater than about 90°. Surface treatmentsunderstood by one of ordinary skill in the art, such as plasma treating,corona treating, chemical oxidation, and etching, can be used to modifythe surface to render the surface more capable of allowing the coatingsubstance to have a suitably high capillary permeation.

[0035]FIG. 5 illustrates an embodiment in which the outer surface ofconing end portions 30 and/or 36 is covered with a layer 50. In such anembodiment, coning end portions 30 and/or 36 can have either porous ornon-porous surfaces, while layer 50 can be made of an absorbentmaterial, such as a sponge. Accordingly, layer 50 can absorb excesscoating substance flowing off of stent 10. In addition, support member20, mandrel 22, and/or lock member 24 can also be covered with layer 50.

[0036] While the device of the present invention has been describedherein as having coning end portions 30 and 36 that support therespective ends of a stent and draw excess coating materials away fromthe stent via pores 44, it should be understood that the presentinvention is not limited thereto. Rather, the stent mounting assembly ofthe present invention can be any device that includes porous regions forsupporting a stent as well as for absorbing excess coating materials tominimize coating defects.

Coating a Stent Using the Mounting Assembly

[0037] The following method of application is being provided by way ofillustration and is not intended to limit the embodiments of mountingassembly 18 of the present invention. A spray apparatus, such as EFD780S spray device with VALVEMATE 7040 control system (manufactured byEFD Inc., East Providence, R.I.), can be used to apply a composition toa stent. EFD 780S spray device is an air-assisted external mixingatomizer. The composition is atomized into small droplets by air anduniformly applied to the stent surfaces. The atomization pressure can bemaintained at a range of about 5 psi to about 20 psi. The droplet sizedepends on such factors as viscosity of the solution, surface tension ofthe solvent, and atomization pressure. Other types of spray applicators,including air-assisted internal mixing atomizers and ultrasonicapplicators, can also be used for the application of the composition.

[0038] During the application of the composition, a stent supported bymounting assembly 18 can be rotated about the stent's centrallongitudinal axis. Rotation of the stent can be from about 1 rpm toabout 300 rpm, more narrowly from about 50 rpm to about 150 rpm. By wayof example, the stent can rotate at about 120 rpm. The stent can also bemoved in a linear direction along the same axis. The stent can be movedat about 1 mm/second to about 12 mm/second, for example about 6mm/second, or for a minimum of at least two passes (i.e., back and forthpast the spray nozzle). The flow rate of the solution from the spraynozzle can be from about 0.01 mg/second to about 0.1 mg/second, morenarrowly about 0.1 mg/second. Multiple repetitions for applying thecomposition can be performed, wherein each repetition can be, forexample, about 1 second to about 10 seconds in duration. The amount ofcoating applied by each repetition can be about 0.1 micrograms/cm² (ofstent surface) to about 40 micrograms/cm², for example less than about 2micrograms/cm² per 5-second spray.

[0039] Each repetition can be followed by removal of a significantamount of the solvent. Depending on the volatility of the particularsolvent employed, the solvent can evaporate essentially upon contactwith the stent. Alternatively, removal of the solvent can be induced bybaking the stent in an oven at a mild temperature (e.g., 60° C.) for asuitable duration of time (e.g., 2-4 hours) or by the application ofwarm air. The application of warm air between each repetition preventscoating defects and minimizes interaction between the active agent andthe solvent. The temperature of the warm air can be from about 30° C. toabout 60° C., more narrowly from about 40° C. to about 50° C. The flowrate of the warm air can be from about 20 cubic feet/minute (CFM) (0.57cubic meters/minute (CMM)) to about 80 CFM (2.27 CMM), more narrowlyabout 30 CFM (0.85 CMM) to about 40 CFM (1.13 CMM). The warm air can beapplied for about 3 seconds to about 60 seconds, more narrowly for about10 seconds to about 20 seconds. By way of example, warm air applicationscan be performed at a temperature of about 50° C., at a flow rate ofabout 40 CFM, and for about 10 seconds. Any suitable number ofrepetitions of applying the composition followed by removing thesolvent(s) can be performed to form a coating of a desired thickness orweight. Excessive application of the polymer in a single applicationcan, however, cause coating defects.

[0040] Operations such as wiping, centrifugation, or other web clearingacts can also be performed to achieve a more uniform coating. Briefly,wiping refers to the physical removal of excess coating from the surfaceof the stent; and centrifugation refers to rapid rotation of the stentabout an axis of rotation. The excess coating can also be vacuumed offof the surface of the stent.

[0041] In accordance with one embodiment, the stent can be at leastpartially pre-expanded prior to the application of the composition. Forexample, the stent can be radially expanded about 20% to about 60%, morenarrowly about 27% to about 55% the measurement being taken from thestent's inner diameter at an expanded position as compared to the innerdiameter at the unexpanded position. The expansion of the stent, forincreasing the interspace between the stent struts during theapplication of the composition, can further prevent “cob web” formationbetween the stent struts.

[0042] In accordance with one embodiment, the composition can include asolvent and a polymer dissolved in the solvent. The composition can alsoinclude active agents, radiopaque elements, or radioactive isotopes.Representative examples of polymers that can be used to coat a stentinclude ethylene vinyl alcohol copolymer (commonly known by the genericname EVOH or by the trade name EVAL), poly(hydroxyvalerate);poly(L-lactic acid); polycaprolactone; poly(lactide-coglycolide);poly(hydroxybutyrate); poly(hydroxybutyrate-co-valerate); polydioxanone;polyorthoester; polyanhydride; poly(glycolic acid); poly(D,L-lacticacid); poly(glycolic acid-co-trimethylene carbonate); polyphosphoester;polyphosphoester urethane; poly(amino acids); cyanoacrylates;poly(trimethylene carbonate); poly(iminocarbonate); copoly(ether-esters)(e.g. PEO/PLA); polyalkylene oxalates; polyphosphazenes; biomolecules,such as fibrin, fibrinogen, cellulose, starch, collagen and hyaluronicacid; polyurethanes; silicones; polyesters; polyolefms; polyisobutyleneand ethylene-alphaolefin copolymers; acrylic polymers and copolymers;vinyl halide polymers and copolymers, such as polyvinyl chloride;polyvinyl ethers, such as polyvinyl methyl ether; polyvinylidenehalides, such as polyvinylidene fluoride and polyvinylidene chloride;polyacrylonitrile; polyvinyl ketones; polyvinyl aromatics, such aspolystyrene; polyvinyl esters, such as polyvinyl acetate; copolymers ofvinyl monomers with each other and olefins, such as ethylene-methylmethacrylate copolymers, acrylonitrile-styrene copolymers, ABS resins,and ethylene-vinyl acetate copolymers; polyamides, such as Nylon 66 andpolycaprolactam; alkyd resins; polycarbonates; polyoxymethylenes;polyimides; polyethers; epoxy resins; polyurethanes; rayon;rayon-triacetate; cellulose; cellulose acetate; cellulose butyrate;cellulose acetate butyrate; cellophane; cellulose nitrate; cellulosepropionate; cellulose ethers; and carboxymethyl cellulose.

[0043] “Solvent” is defined as a liquid substance or composition that iscompatible with the polymer and is capable of dissolving the polymer atthe concentration desired in the composition. Examples of solventsinclude, but are not limited to, dimethylsulfoxide (DMSO), chloroform,acetone, water (buffered saline), xylene, methanol, ethanol, 1-propanol,tetrahydrofuran, 1-butanone, dimethylformamide, dimethylacetamide,cyclohexanone, ethyl acetate, methylethylketone, propylene glycolmonomethylether, isopropanol, isopropanol admixed with water, N-methylpyrrolidinone, toluene, and combinations thereof.

[0044] The active agent could be for inhibiting the activity of vascularsmooth muscle cells. More specifically, the active agent can be aimed atinhibiting abnormal or inappropriate migration and/or proliferation ofsmooth muscle cells for the inhibition of restenosis. The active agentcan also include any substance capable of exerting a therapeutic orprophylactic effect in the practice of the present invention. Forexample, the agent can be for enhancing wound healing in a vascular siteor improving the structural and elastic properties of the vascular site.Examples of agents include antiproliferative substances such asactinomycin D, or derivatives and analogs thereof (manufactured bySigma-Aldrich 1001 West Saint Paul Avenue, Milwaukee, Wis. 53233; orCOSMEGEN available from Merck). Synonyms of actinomycin D includedactinomycin, actinomycin IV, actinomycin I₁, actinomycin X₁, andactinomycin C₁. The active agent can also fall under the genus ofantineoplastic, antiinflammatory, antiplatelet, anticoagulant,antifibrin, antithrombin, antimitotic, antibiotic, antiallergic andantioxidant substances. Examples of such antineoplastics and/orantimitotics include paclitaxel (e.g. TAXOL° by Bristol-Myers SquibbCo., Stamford, Conn.), docetaxel (e.g. Taxotere®, from Aventis S.A.,Frankfurt, Germany) methotrexate, azathioprine, vincristine,vinblastine, fluorouracil, doxorubicin hydrochloride (e.g. Adriamycin®from Pharmacia & Upjohn, Peapack N.J.), and mitomycin (e.g. Mutamycin®from Bristol-Myers Squibb Co., Stamford, Conn.) Examples of suchantiplatelets, anticoagulants, antifibrin, and antithrombins includesodium heparin, low molecular weight heparins, heparinoids, hirudin,argatroban, forskolin, vapiprost, prostacyclin and prostacyclinanalogues, dextran, D-phe-pro-arg-chloromethylketone (syntheticantithrombin), dipyridamole, glycoprotein IIb/IIIa platelet membranereceptor antagonist antibody, recombinant hirudin, and thrombininhibitors such as AngiomaxT™ (Biogen, Inc., Cambridge, Mass.) Examplesof such cytostatic or antiproliferative agents include angiopeptin,angiotensin converting enzyme inhibitors such as captopril (e.g.Capoten® and Capozide® from Bristol-Myers Squibb Co., Stamford, Conn.),cilazapril or lisinopril (e.g. Prinivil® and Prinzide® from Merck & Co.,Inc., Whitehouse Station, N.J.); calcium channel blockers (such asnifedipine), colchicine, fibroblast growth factor (FGF) antagonists,fish oil (omega 3-fatty acid), histamine antagonists, lovastatin (aninhibitor of HMG-CoA reductase, a cholesterol lowering drug, brand nameMevacor® from Merck & Co., Inc., Whitehouse Station, N.J.), monoclonalantibodies (such as those specific for Platelet-Derived Growth Factor(PDGF) receptors), nitroprusside, phosphodiesterase inhibitors,prostaglandin inhibitors, suramin, serotonin blockers, steroids,thioprotease inhibitors, triazolopyrimidine (a PDGF antagonist), andnitric oxide. An example of an antiallergic agent is permirolastpotassium. Other therapeutic substances or agents which may beappropriate include alpha-interferon, genetically engineered epithelialcells, rapamycin and dexamethasone. Exposure of the active ingredient tothe composition should not adversely alter the active ingredient'scomposition or characteristic. Accordingly, the particular activeingredient is selected for compatibility with the solvent or blendedpolymer-solvent.

[0045] Examples of radiopaque elements include, but are not limited to,gold, tantalum, and platinum. An example of a radioactive isotope isP³². Sufficient amounts of such substances may be dispersed in thecomposition such that the substances are not present in the compositionas agglomerates or flocs.

[0046] While particular embodiments of the present invention have beenshown and described, it will be obvious to those skilled in the art thatchanges and modifications can be made without departing from thisinvention in its broader aspects. Therefore, the appended claims are toencompass within their scope all such changes and modifications as fallwithin the true spirit and scope of this invention.

What is claimed is:
 1. An apparatus for supporting a stent during aprocess of coating the stent, comprising: a member for supporting astent during the coating process, wherein a section of the memberincludes a porous surface capable of receiving the coating substanceduring the coating process.
 2. The apparatus of claim 1, wherein thepores have a diameter between about 0.2 microns and about 50 microns. 3.The apparatus of claim 1, wherein the member includes a first member formaking contact with a first end of the stent and a second member formaking contact with a second end of the stent and wherein the pores arelocated on at least a region of the surface of the first or secondmembers.
 4. The apparatus of claim 3, wherein the first or second memberis made from a metallic material selected from a group of 300 Seriesstainless steel, 400 Series stainless steel, titanium, tantalum,niobium, zirconium, hafnium, and cobalt chromium alloys.
 5. Theapparatus of claim 3, wherein the first or second member is made from apolymeric material.
 6. The apparatus of claim 5, wherein the polymericmaterial is selected from a group of regenerated cellulose, celluloseacetate, polyacetal, polyetheretherketone, polyesters, highly hydrolyzedpolyvinyl alcohol, nylon, polyphenylenesulfide, polyethylene,polyethylene terephthalate, polypropylene, and combinations thereof. 7.The apparatus of claim 3, wherein the first or second member is madefrom a ceramic material selected from a group of zirconia, silica,glass, sintered calcium phosphates, calcium sulfate, and titaniumdioxide.
 8. The apparatus of claim 3, wherein the first and secondmembers have inwardly tapered ends that penetrate at least partially inthe first and second ends of the stent and are in contact with the firstand second ends of the stent.
 9. The apparatus of claim 3, additionallycomprising a third member for extending within the stent and forsecuring the first member to the second member.
 10. The apparatus ofclaim 9, wherein the outer surface of the third member does not makecontact with the inner surface of the stent.
 11. The apparatus of claim1, wherein the member includes a first member for making contact with afirst end of the stent, a second member for making contact with a secondend of the stent, and a layer disposed on the surface of the first orsecond member to absorb coating material that comes into contact withthe layer.
 12. A mounting assembly for supporting a stent during theapplication of a coating composition onto the stent, comprising: asupport member including means for receiving and containing the excesscoating composition applied to the stent during the application process.13. The mounting assembly of claim 12, wherein the means is defined by aplurality of pores made on a selected region of the support member. 14.The mounting assembly of claim 12, wherein the support member includes afirst member for supporting a first end of the stent and a second memberfor supporting a second end of the stent and wherein the surface of thefirst or second member includes cavities.
 15. The mounting assembly ofclaim 14, wherein the support member additionally includes a thirdmember for extending within the stent and for securing the first memberto the second member and wherein the distance between the first memberand the second member can be adjusted by inserting the third memberdeeper into the first member or the second member.
 16. The mountingassembly of claim 12, wherein the support member includes a first memberfor supporting a first end of the stent, a second member for supportinga second end of the stent, and a layer disposed on the surface of thefirst or second member to absorb coating material that comes intocontact with the layer.
 17. A method of coating a stent, comprising:positioning a stent on a mounting assembly, wherein a section of themounting assembly includes a porous surface; and applying a coatingcomposition to the stent, wherein at least some of the coatingcomposition that overflows from the stent is received by the pores. 18.The method of claim 17, wherein the mounting assembly includes a firstmember for making contact with a first end of the stent and a secondmember for making contact with a second end of the stent and wherein thepores are located on at least a region of the surface of the first orsecond members.
 19. The method of claim 17, additionally comprising atleast partially expanding the stent prior to the act of applying. 20.The method of claim 17, wherein the coating composition includes asolvent, a polymer dissolved in the solvent, and optionally atherapeutic substance.
 21. The method of claim 17, additionallycomprising rotating the stent about the longitudinal axis of the stentduring the act of applying.
 22. The method of claim 17, additionallycomprising moving the stent in a linear direction along the longitudinalaxis of the stent during the act of applying.
 23. The method of claim17, wherein the act of applying a coating composition comprises sprayingthe coating composition onto the stent.
 24. A support assembly for astent, comprising: a member for supporting a stent, wherein the memberincludes an absorbing layer for at least partially absorbing some of thecoating material that comes into contact with the absorbing layer.